The government has so far failed in its attempt to increase the percentage of youngsters from working-class homes going to university, says a damning report.

The National Audit Office, the public spending watchdog, says the level has remained unchanged at 28 per cent for six years. The worst offenders are Oxford and Cambridge – both of whom have only 9 per cent of students from disadvantaged backgrounds, compared with 28 per cent nationally.

The report blames the lack of financial support and the poor use of £200m in government funds a year to help youngsters from deprived backgrounds. It concedes that the number of students from poorer backgrounds has doubled but so has the number from more affluent homes.

It also points out that Britain is the only one of 10 countries committed to widening participation in higher education to fail to give any mandatory element of grant towards student living costs. Those who give financial aid include Australia, Finland, France, Germany, Ireland, the Netherlands, Spain, Sweden and the United States.

"Young people not currently in higher education told our consultants of their concerns about financing studies," says the report. "Many heard about debts after studying, which they felt were too large to contemplate. Some had found that higher education institutions provided information about additional financial help too late and only after they had decided against further study."

The report says that students from working-class homes spend about twice as much time in paid employment to reduce their debt, while they are studying, as those from middle-class homes.

A spokesman for the NAO said: "We don't feel [funding] is well targeted. The universities also say it doesn't reflect the actual cost of going out to attract students."

The NAO says the cash goes to universities with poor records in attracting students from non-traditional backgrounds – such as Oxford and Cambridge – rather than those such as Wolverhampton which, with 47 per cent of students from poorer homes, have the best records in widening participation. Even when they have climbed the hurdle of seeking a university place people from poor social backgrounds have less success than middle-class students in converting applications into places.

The report goes on to praise some universities for taking positive steps to recruit from non-traditional university backgrounds. In Staffordshire, youngsters can be given the guarantee of a place if they complete an application a year before they would normally apply through the Ucas admissions service. The University of Bristol will reduce grade requirements in offering places to students from low- performing schools. Research shows that they go on to gain higher grade degree passes.

The report also attacks universities for charging up to £200 for taster courses for youngsters to give them an insight into university life, saying this deters people from groups with low representation.

David Rendel, the Liberal Democrat higher education spokesman, said: "This report confirms that young people from poorer backgrounds are much less likely to go on to higher education and that the abolition of the maintenance grant has probably made the situation worse. Public funding per student is now even lower than under the Conservatives. This decline must be reversed."

Margaret Hodge, the Higher Education minister, said: "We are already looking at how to simplify and target effectively the current support available. Making year-on-year progress towards fair access and bearing down on rates of non-completion remain government priorities."

A separate report from the NAO praises universities for maintaining a degree-pass rate of 77 per cent despite the considerable increase in numbers.Six per cent of students switch courses or institutions while 16 per cent obtain no qualification.